JP2004242320A - Large capacity optical router utilizing electric buffer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical router for overcoming the limitations of an all optical router system and a high speed IP router system. <P>SOLUTION: The optical router applies inverse wavelength multiplexing to a wavelength signal received from an add port, converts an optical frame into an electric signal, processes the electric signal, and provides an output of an optical frame, includes an optical switch for switching the optical frame, converts the optical frame after switching into an electric signal, processes the signal, and provides an output of optical frames, applies wavelength multiplexing to the optical frames, transmits the resulting optical frame to another optical router, converts the optical frame outputted to an IP router after the switching into an electric signal, processes the electric signal, and provides an output of an optical frame, recognizes header information, controls an optical switch connecting state, re-inserts a header, converts an IP packet into an optical frame, and converts the optical frame into an IP packet. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a large-capacity optical router for high-speed exchange of data traffic such as Internet Protocol (IP) packets and Ethernet (registered trademark, the same applies hereinafter) frames in units of optical frames, and in particular, uses an electric buffer. High-capacity optical router.

  2. Description of the Related Art Generally, in response to a rapid increase in data services such as the Internet, moving images, and video on demand (VOD), a large amount of data traffic of several hundreds Gb / s to several Tb / s occurs in a network. Therefore, a large-capacity router / switch having a capacity of several hundred Gb / s to several Tb / s is required for efficient switching or routing.

  In order to construct such a large-capacity IP router, conventionally, several tens of small-capacity IP routers are interconnected to obtain a large-capacity effect. However, such a scheme has a problem that 50-60% of capacity is simply interconnected and used, so that bandwidth is wasted and the number of IP routers increases rapidly according to required capacity. . Therefore, there has been a need for a router / switch having as large a capacity as possible to reduce the number of equipment.

  Conventionally, two methods are mainly used to configure such a large-capacity router.

  FIG. 1 is a diagram showing a configuration of a conventional all optical router, which discloses one method for configuring a large-capacity router.

  As shown, optical data is exchanged through a spatial switch 14 including an on-off gate switch 14-3, and when a collision occurs between optical data, a tunable wavelength converter and an optical fiber delay line are used. The buffer 16 is used to resolve the collision. In addition, optical data is switched using a variable wavelength converter and a wavelength router such as an N × N AWG (Arrayed Waveguide Grating), and collision between data is resolved through an optical fiber delay line.

  Another method implements a large-capacity IP router employing a high-speed interface of 10 Gb / s or more. In this method, the header of an input packet is recognized for each packet, an electric switch is driven, and packet routing / switching is performed. And the collision between packets is resolved through an electrical buffer. For this reason, large-capacity IP routers of this type have been developed as a type of terabit router.

  In the all-optical router system as shown in FIG. 1, an optical fiber delay line is used to resolve collision between optical data due to the absence of an optical memory. However, if the switching capacity of the optical router increases and the length of the optical data increases, the length of the optical fiber delay line may reach several tens to several hundreds of kilometers, which increases the size of the system. There is a problem that not only causes the complexity but also greatly increases the complexity.

  In addition, since the optical fiber delay line utilizes the effect that an optical signal is delayed in the optical fiber, system control is extremely difficult, and a signal intensity difference between optical data due to loss occurring in the optical fiber occurs. I do. Most all-optical router systems use many variable wavelength converters for switching or buffering. The tunable wavelength converter is generally composed of a tunable laser and a number of semiconductor optical amplifiers (SOAs), and has a problem that the manufacturing cost is high.

  Further, the stabilization speed of the tunable wavelength laser is as slow as several ms to several tens ms, which is not suitable for a high-speed optical router. The all-optical router has a problem that it is very difficult to monitor the signal performance and reproduce the signal. Further, since all optical routers of FIG. 1 use many optical couplers, there is a disadvantage that optical data has a large path loss.

  In the case of an electrical IP router, forwarding must be performed by recognizing a header for each input packet, which has a large speed limit for processing a high-speed packet of 10 Gb / s. To date, no 40 Gb / s interface has been developed.

  In order to process a 64-byte packet having a speed of 10 Gb / s and 40 Gb / s as a current technology, a forwarding speed of 15 Mp / s and 60 Mp / s is required, respectively. In addition, not only packets to be added / dropped but also packets to be passed through must be processed, so that the processing load on the router increases, which wastes processing capacity. .

  High-capacity IP routers should use high-speed electric switches, but electric switches have limitations in speed and expandability. Further, when configuring a large-capacity node requiring a capacity of several Tb (terabit) / s or more, several tens or more large-capacity routers are required, which not only weights the complexity of the node but also increases the And increase operating costs.

  An object of the present invention to solve such problems is to provide a large-capacity optical router that overcomes limitations of the all-optical router system and the high-speed IP router system.

  Another object of the present invention is to solve the problems of the variable wavelength converter and the optical fiber delay line buffer, which are problems in all-optical routers by using an electrical buffer, and to easily monitor the signal performance and reproduce the signal of an optical signal. To provide a large capacity optical router.

  Still another object of the present invention is to provide a large-capacity optical router that solves the problem of electric switch speed and scalability by using an optical switch having a switching speed of several ns, unlike the high-speed IP router method. It is in.

  Still another object of the present invention is to convert a packet into an optical frame of a fixed length by an edge traffic aggregator and perform switching, thereby limiting forwarding and switching speed of a high-speed IP router. It is to provide a large-capacity optical router to be solved.

  Still another object of the present invention is to provide an equipment occupying area and construction by greatly reducing the number of equipments constituting a node by having a capacity of Tb / s or more even in a single structure. An object of the present invention is to provide a large-capacity optical router capable of greatly reducing costs and operation costs.

  In order to achieve the above object, an optical router according to the present invention comprises a number of input ports, a number of output ports, an add port for inputting data received from a multi-terminal IP router, and a multi-port terminal. A drop port for outputting to an IP router, a wavelength demultiplexer for demultiplexing a wavelength signal input through an input port and an add port, and an optical frame input from the wavelength demultiplexer as an electric signal. An input interface unit that outputs an optical frame after conversion and processing, an optical switch that switches an optical frame output from the input interface unit, and an optical frame that is switched and output by the optical switch and converted to an electric signal Output interface section that outputs the data as an optical frame after processing A wavelength multiplexer that wavelength-multiplexes the output of the optical network and transmits it to another optical router, and converts an optical frame output to the multi-terminal IP router out of optical frames switched by the optical switch into an electric signal for processing. A drop interface unit for outputting as an optical frame after output, a header processing unit for recognizing header information for optical router control, an optical switch control unit for controlling an optical switch connection state for optical frame switching, and an optical router output. A header re-insertion unit for re-inserting the header, an ingress unit for converting an IP packet input from the composite terminal IP router into an optical frame, and a conversion of the optical frame into an IP packet for transmission to the composite terminal IP router And an edge traffic aggregator having an egress portion.

  The wavelength demultiplexer can be composed of a plurality of wavelength demultiplexers. Such an optical router converts a packet input from a composite terminal IP router into an optical frame of a fixed length according to a destination address by an edge traffic aggregator, and then performs optical / electric / optical conversion at an input interface unit. After processing the optical frame and performing switching by the optical switch, the output interface unit transmits the optical frame to the next optical router node or edge traffic concentrator via optical / electric / optical conversion. Can be. Also, the ingress part of the edge traffic aggregator converts a packet input from the multi-terminal IP router into a data frame of a fixed length according to the destination address, and has a speed that is an integral multiple of the data frame. The header can be generated and combined with the data frame and transmitted as an optical frame. Further, the egress unit of the edge traffic aggregator may receive the optical frame dropped by the drop interface unit, separate the IP frame into IP packets, and transmit the IP packets to the composite terminal IP router. The input interface unit includes a header length detector that detects a header start point and a header length, and a switch that separates a header from a data frame and sends the header to a header processing unit. The output interface unit includes an optical switch. And a header inserter for inserting a new header into the optical frame switched in step (1).

  More specifically, the input interface unit includes an optical receiver that converts an optical frame input from the wavelength demultiplexing unit into an electric signal, a buffer that stores the frame converted by the optical receiver for synchronization, A header length detector that extracts a header length to separate the header from the frame converted by the optical receiver, a switch that separates the header and data from the frame output from the buffer, and a switch that separates the data separated by this switch. A queue for storing before switching for collision resolution, and an optical transmitter for receiving data from the queue, restoring a frame converted into an electric signal into an optical frame, and transmitting the frame to an optical switch The header processing unit at this time reads the address with reference to the header separated by the switch, determines the output time, and determines a new header. It may be configured to send to the header reinserting section. In this case, it is preferable that a guard time having a fixed interval is provided between the header of the frame input to the switch and the data frame to prevent data loss when separating. The queue of the input interface unit includes an electrical switch for switching input data for each destination and outputting the data, and a plurality of buffers provided for the number of destinations for receiving and storing data for each destination and accumulating a predetermined amount of data. And a combiner for combining the outputs of these buffers.

  Alternatively, the input interface unit comprises: an optical receiver for converting an optical frame input from the wavelength demultiplexing unit into an electric signal; a buffer for storing the frame converted by the optical receiver for synchronization; A header length detector that extracts a header length to separate the header from the frame converted by the receiver, a switch that separates the header and data from the frame output from the buffer, and a large number of data separated by the switch Are stored before switching for collision resolution, and a queue for multiplex output and data output from this queue are input, and the frame converted to the electric signal is restored to an optical frame and transmitted to the optical switch. And a plurality of optical transmitters.

  The output interface unit converts the optical data switched by the optical switch into an electric signal, an optical receiver, a buffer for temporarily storing data output from the optical receiver, and a data output from the buffer. , A header inserter for reinserting the header by the header reinsertion unit, and an optical transmitter for transmitting the data after the header combination as optical data to the next node. Alternatively, the output interface unit includes a number of optical receivers for converting optical data switched by the optical switch into electric signals, a number of buffers for temporarily storing data output from the optical receivers, and a number of buffers. A combiner that combines the data output from the buffer, a header inserter that reinserts the header by the header reinsertion unit into the data output from the combiner, and the next node as the optical data after the header is combined. And an optical transmitter for transmitting the signal to the optical transmitter.

  The ingress part of the edge traffic aggregator has a plurality of optical receivers for receiving packet data input from the multi-terminal IP router, and is connected to each of the optical receivers to perform functions such as packet forwarding. A packet processing unit, an address table for providing address information for packet forwarding, a first electric switch for switching an output from the packet processing unit for generating an optical frame, and a number of buffers, A data frame assembler for converting a packet switched by the first electric switch into a predetermined amount of frames, a controller and a scheduler for determining an output order and a wavelength of the frame generated by the data frame assembler; Output order and wavelength are determined by instrument and scheduler A second electrical switch for transmitting the extracted frame, a number of header inserters for inserting a header before optical modulation of the frame output from the second electrical switch, and optical modulation of the frame after the header combination. And a wavelength multiplexer for wavelength division multiplexing the optical frame after optical modulation. The data frame assembler stores the switched packets in destinations according to destinations and stores them in a number of buffers. When a certain amount of data is accumulated in each of the buffers, the data frame assembler processes the data for each buffer, and a controller and a scheduler perform the processing. The output order and wavelength of the optical frame can be determined by grasping the data amount of each buffer of the data frame assembler and the like.

  The egress part of the edge traffic aggregator is a wavelength demultiplexer for demultiplexing the optical frame dropped and wavelength-division multiplexed by the drop interface part, and converts the demultiplexed optical frame into an electric signal. A plurality of optical receivers, a data frame disassembler for separating the frame after the electrical signal conversion into IP packets and separating the frames into detail destinations, and a scheduler for controlling the output order of the IP packets separated into detail destinations , A packet processing unit for processing an IP packet output from the data frame disassembler through a process such as forwarding, an address table for providing an address of a packet to be processed by the packet processing unit, and a processing by the packet processing unit. To switch the received packet to the correct destination IP router. A switch, and a plurality of optical transmitters for optically modulating the switched packet by the electric switch, can be made of.

  The present invention solves the problem of the price and speed limitation of the variable wavelength converter and the optical fiber delay line buffer of the conventional all-optical router system by utilizing the optical / electrical / optical conversion, and monitors the signal performance and reproduces the signal. To facilitate.

  Also, unlike the electric router method, the use of a high-speed optical switch solves the speed and scalability problems of the electric switch.

  In addition, since switching is performed in units of optical frames of a fixed length, the forwarding and switching speed limitations of the conventional IP router are solved. That is, while a conventional IP router requires a forwarding speed of several tens of Mp / s, the optical router of the present invention performs switching in units of an optical frame of a fixed length to reduce the forwarding request speed by several hundreds. kp / s to several Mp / s, and the processing load on the router can be greatly reduced.

  In addition, since a single structure can have a capacity of Tb / s or more, the number of equipment required for a node can be significantly reduced. In conclusion, unlike the conventional large-capacity IP router, the optical router according to the present invention can greatly reduce the node area, the construction cost and the operation cost, so that it is effective in the future large-capacity communication network. It is expected to be used for

  Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings. In the following description, a detailed description of related known functions and configurations will be omitted for the purpose of clarifying only the gist of the present invention.

  FIG. 2 is a diagram showing a configuration example of a large-capacity optical router according to the present invention.

  This large-capacity optical router has N input ports (INPUT 1 to INPUT N), N output ports (OUTPUT 1 to OUTPUT N), and an add port which is a terminal for inputting data received from a multi-terminal IP router. (Add), and a drop port (Drop) which is a terminal for outputting data to be output to the composite terminal IP router.

  The wavelength demultiplexing unit 20 wavelength demultiplexes the wavelength signals (λ1 to λn) input through the input ports (INPUT 1 to INPUT N) and the add port (Add). The wavelength demultiplexing unit 20 is composed of N + 1 wavelength demultiplexers (WDM). The input interface unit 30 converts an optical frame input from the wavelength demultiplexer into an electric signal and processes it. The output terminals of one wavelength demultiplexer are connected to n input interfaces corresponding to the wavelength signals (λ1 to λn). The optical switch (on-off Gate Switch) 40 performs high-speed switching of an optical frame output from the input interface unit 30. The output interface unit 50 processes the optical frame switched and output by the optical switch 40. The wavelength multiplexing unit 70 wavelength multiplexes the output of the output interface unit 50 and transmits the multiplexed output to another large-capacity optical router. The drop interface unit 60 processes an optical frame output from the wavelength multiplexing unit 70 to the multi-terminal IP router. The header processing unit 75 recognizes header information for controlling the optical router. The optical switch control unit 80 controls the connection state of the optical switch for switching the optical frame. The header re-insertion unit 90 re-inserts the header into the output of the optical router. The edge traffic aggregator 100 includes an ingress part (ingress part) 100-1 and an egress part (egress part) 100-2. The ingress unit 100-1 converts an IP packet input from the multi-terminal IP router into an optical frame, and the egress unit 100-2 converts the optical frame into an IP packet and transmits it to the IP router.

  The input / output terminals connected to the wavelength (de) multiplexing units 20 and 70 perform data transmission / reception between the large-capacity optical routers, and the ingress unit 100-1 of the edge traffic aggregator 100 uses the complex terminal IP router. , And the egress unit 100-2 of the edge traffic aggregator 100 processes the data output to the multi-terminal IP router.

  FIG. 3 shows the input interface unit 30 of FIG. 2 in detail.

  The optical receiver 120 converts the optical frame input from the wavelength demultiplexer 20 into an electric signal. The buffer 122 stores the frame converted by the optical receiver 120 for synchronization. A header length detector 123 extracts a header length to separate the header from the converted frame. Switch 124 separates the header and data from the frame. Queue 125 stores the data separated by switch 124 for conflict resolution before being switched. The optical transmitter 126 receives the data from the queue 125, restores the frame converted into an electric signal into an optical frame for transmitting the data to the optical switch, and transmits the optical frame. The header processing unit 75 reads the address with reference to the header of the input frame. Also, the header processing unit 75 determines when to output the data, and when outputting the data, sends a new header to the header re-insertion unit 90 for insertion.

  FIG. 4 shows the queue 125 of the input interface 30 of FIG. 3 in detail.

  The queue 125 includes a 1 × N electrical switch 128, N buffers 129, and a combiner 130 to overcome input buffering limitations. The switch 128 switches the input data for each destination and transmits the data to the buffers 1 to N129. Buffers 129 are provided for the number of destinations, and receive and store data for each destination, and when a certain amount of data is accumulated, transmit the data to the optical transmitter 126 via the coupler 130. The input interface 30 is connected to a header processing unit 75 for processing the separated header. The header processing unit 75 grasps the destination of the data using the header, and determines and controls the data output timing.

  FIG. 5 shows the output interface unit 50 of FIG. 2 in detail.

  The output interface unit 50 includes an optical receiver 140 for converting optical data switched by the optical switch 40 into an electric signal, a buffer 141 for temporarily storing data for header reinsertion, a header inserter 142 for reinserting a header, and a header connection. It comprises an optical transmitter 143 for performing optical modulation later and transmitting optical data to the next node. The header inserter 142 of the output interface 50 receives and re-inserts the header from the header re-insertion unit 90 that generates a header to be re-inserted for re-insertion of the header. The header re-insertion unit 90 grasps the destination based on the header information received from the input interface 30, and generates and provides a new header when outputting.

  On the other hand, the drop interface unit 60 has the same structure as the output interface unit 50 of FIG. Since the output of the drop interface unit 60 is reprocessed by the egress unit 100-2 of the edge traffic aggregator 100, the header inserter 142 is not required.

  FIG. 6 is a diagram showing a configuration of an optical frame separated into a header and a data frame by the switch 124 of FIG.

Reference sign T _HEADER indicates a header, and T _DATA indicates a data frame. _TG indicates a guard time, which is a portion indicating a time when the switch 124 separates the header and the data frame. As shown, _TG is used to prevent data loss when the switch separates the header and the data frame.

  FIG. 7 is a diagram showing the ingress unit 100-1 of the edge traffic aggregator 100 of FIG. 2 in detail.

  The ingress unit 100-1 transmits data received from the multi-terminal IP router to the optical router through an add port (Add) and processes the data. The ingress unit 100-1 is connected to the M optical receivers 150 for receiving packet data input from the multi-terminal IP router, and is connected to the optical receivers 150, and performs packet forwarding and other functions. A processing unit 151, an address table 152 for providing address information for packet forwarding, an electric switch 153 for switching an input from the packet processing unit 151 to K buffers described later for generating an optical frame, and the K switches A data frame assembler 154 for converting a switched packet into an optical frame by providing a buffer, a controller and a scheduler 155 for determining the output order and wavelength of the optical frame generated by the data frame assembler 154, and the output order and wavelength The determined optical data will be described later. An electrical switch 156 for transmitting to the optical transmitter 158, n header inserters 157 for inserting a header before optical modulation, and n optical transmitters for optically modulating an optical frame combined with the header. The optical transmission unit 158 includes a wavelength multiplexer 159 that performs wavelength division multiplexing of an optical modulation signal.

  The data frame assembler 154 divides the switched packets into destinations and stores them in the buffers 1 to K. When a certain amount of data is accumulated, the data is processed by the buffers. The controller and scheduler 155 determines the output order and wavelength of the optical frame by grasping the data amount of each buffer of the data frame assembler 154 and the like.

  FIG. 8 is a diagram showing the egress unit 100-2 of the edge traffic aggregator 100 of FIG. 2 in detail.

  The egress unit 100-2 receives the output of the drop interface unit 60 and processes data output to the multi-terminal IP router. The egress unit 100-2 includes a wavelength demultiplexer 160 for demultiplexing the wavelength division multiplexed optical signal dropped by the optical router, n optical receivers 161 for converting an optical frame into an electric signal, and a frame. A data frame disassembler 162 for separating IP packets into detail destinations, a scheduler 163 for controlling the output order of IP packets separated for detail destinations, and IP forwarding through processes such as forwarding. A packet processing unit 164 for processing the packet, an address table 165 for providing the address of the packet, an electric switch 166 for switching the processed packet to a correct destination IP router, and M optical transmitters for optically modulating the switched packet 167.

  FIG. 9 shows another embodiment of the input interface unit 30 of FIG. 3 for improving the switching efficiency of the optical router.

  The difference from FIG. 3 described above is that the queue 185 generates a large number (for example, K) of outputs instead of a single output. The number of the optical transmitters 186 is correspondingly provided. In this case, since the data is transmitted according to the destinations, the processing speed is improved. Multiple data frames output from multiple buffers (not shown) of the queue 185 are optically modulated by multiple optical transmitters 186 and input to the optical switch.

  More specifically, the input interface unit 30 of FIG. 3 described above uses the multiplexing buffer 129 of FIG. 4 to prevent the HOL (head of line) blocking problem, but the output of the queue 125 is one. Therefore, the buffer capacity in the queue increases. In order to solve this, by providing a multiplexed output together with a multiplexed buffer to the queue 185 as shown in FIG. 9, the switching efficiency can be increased while reducing the buffer capacity. By adjusting the number of multiplexed outputs of the queue 185, the buffer capacity and the switching efficiency can be adjusted. Since the queue 185 has multiple outputs, the input interface unit 30 requires a large number of optical transmitters 186. Also, the size of the optical switch 40 is increased by K times.

  FIG. 10 is a diagram showing another embodiment of the output interface unit 50 of FIG.

  The difference from FIG. 5 described above is that a large number of optical receivers and buffers (eg, K optical receivers and K buffers) are provided. Further, a coupler 193 is further provided. By providing a large number of optical receivers and buffers in this way, data can be processed for the same destination and the speed can be improved.

  The operation of the optical router according to the present invention having the above-described configuration will be specifically described as follows.

  First, the operation of the ingress unit 100-1 of the edge traffic collector 100 of FIG. 7 will be described. The IP packet transmitted from the multi-terminal IP router mainly has a wavelength of 1.3 mm, and is converted into an electric signal by the optical receiver 150 of the ingress unit 100-1. The converted packet is referred to by the packet processing unit 151 with reference to the address table 152 to determine the destination port and the output order. The data frame assembler 154 in the ingress unit 100-1 has a buffer having only destination addresses (for example, K buffers). Therefore, the packet whose destination port and output order are determined by the packet processing unit 151 is switched by the M × K electrical switch 153 to the buffer of the data frame assembler 154 that matches the destination address. When a data frame having a predetermined time length is formed in the buffer in the data frame assembler 154, an output request signal is transmitted to the controller and the scheduler 155. Upon receiving the output request signal, the controller and scheduler 155 checks the status of the output wavelength channel to determine whether there is a currently available channel. If no wavelength channel is available, the data frame waits until an available channel occurs in the buffer. If there is an available wavelength channel, the data frame in the buffer is switched by the K × n electrical switch 156 to the optical transmitter 158 having the selected wavelength channel. At this time, the header is reinserted into the data frame by each header inserter 157 and switching is performed.

Explaining the reinsertion of the header, the controller and scheduler 155 generates a header signal indicating the destination address of the data frame and the like, and the header signal and the switched data frame are combined by the header inserter 157 and the optical transmission is performed. Switch to section 158. The structure of the combined frame is shown in FIG. 6, where the header is transmitted before the data frame by the guard time. The header and the data frame have fixed lengths of _{TH and TDF} , respectively. Also each header and the data frame R _H [b / s], has a different data rate of R _DF [b / s], the rate of the data frame is an integral multiple of the header frame speed (R _{DF = n} · _RH ).

  For example, if the data frame is 10 Gb / s, the header frame can use 1.25 Gb / s. The header and the data frame each include a preamble so that the start point can be recognized. As described above, the optical frame is optically modulated by the optical transmission unit 158, then wavelength-multiplexed by the wavelength multiplexer 159, and transmitted to the add port (Add) of the optical router. That is, the header and the data frame are modulated at the same wavelength and transmitted.

  Meanwhile, of the optical frames switched by the optical router, the frame transmitted to the composite terminal IP router is input to the egress unit 100-2 of the edge traffic aggregator 100 through the drop interface unit 60.

  The operation of the egress unit 100-2 of the edge traffic aggregator will be described in detail with reference to FIG.

  The input optical signal is wavelength-demultiplexed by the wavelength demultiplexer 160, and then converted into an electric signal by the optical receiver 161. The converted data frame is separated by a data frame disassembler 162 into original IP packet units. The output order of the separated IP packet is given by the scheduler 163, and then the packet processing unit 164 searches the address table 165 to be transmitted to the destination IP router, and performs a forwarding process. Switching is performed by the switch 166. The switched packet is transmitted by the optical transmission unit 167 to the destination compound terminal IP router.

  2, the wavelength multiplexed optical frame signal output from the ingress unit 100-1 of the edge traffic aggregator and the wavelength multiplexed optical frame input to the optical router are demultiplexed by the wavelength demultiplexer 20. After that, it is input to the input interface unit 30.

  The optical frame input to the input interface unit 30 is converted into an electric signal by the optical receiver 120 in FIG. The converted electric signal is input to the buffer 122 and the header length detector 123. The header length detector 123 detects the preamble of the header to determine the start point and length of the header. While detecting the header length, the frame is temporarily stored in a buffer. When the detection of the header start point and the length is completed, the frame stored in the buffer 122 is input to the switch 124. The switch 124 uses the header start point and the header length information detected by the header length detector 123. Separate header and data frame. The separated header is input to the header processing unit 75, and the data frame is input to the queue 125.

  After reading information such as a destination address in the header separated through the forwarding process, the header processing unit 75 determines an output order of the data frames through a scheduling process. The data frame is stored in the queue 125 having the configuration as shown in FIG. 4 until the scheduling is completed in the header processing unit 75. However, the head of line (HOL) blocking problem, which is a problem of input buffering, is avoided. To resolve, the queue 125 has N buffers 129. The data frame output from the queue 125 by the scheduling is optically modulated by the optical transmitter 126 and then input to the optical switch. At this time, the optical transmitter 126 can use an inexpensive device for short reach.

  In the conventional system, when the data packet is 10 Gb / s, the header processing unit should also perform high-speed processing of 10 GHz. However, the present invention uses a header having a speed of 1 / n of the data frame speed. The processing unit 75 only needs to have a processing speed of 'data rate / n' Hz.

  According to the conventional method, the header processing unit should perform high-speed processing of several tens of Mp / s in order to process a packet having a short length of about 64 bytes (bytes). Since the data frame having a long length is generated by the aggregator 100, the speed load of the header processing is reduced to several tens to hundreds of times as compared with the conventional method. Then, the header processing unit 75 generates a control signal to the optical switch control unit 80 according to the forwarding and scheduling results, and the data frame transmitted to the optical switch 40 is rapidly switched to the destination according to the signal. . The header processing unit 75 transmits the header change information to the header reinsertion unit 90 for reinserting the header.

  The optical data frame switched by the optical switch 40 is input to the output interface unit 50. This signal is further converted into an electric signal by the optical receiver 140 of FIG. Then, the header re-insertion unit 90 generates a new header using the header change information transmitted from the header processing unit 75, and transmits this signal to the header insertion unit 142. At this time, the data frame stored in the buffer 141 is output, combined with the header by the header re-insertion unit 90, and optically modulated by the optical transmitter 143. The subsequent data frame is wavelength multiplexed by the wavelength multiplexing unit 70 and then transmitted to another optical router.

  The data frame switched by the optical switch 40 is output to the multi-terminal IP router unless it is output to another large-capacity optical router. That is, the data frame is transmitted to the egress unit 100-2 of the edge traffic aggregator via the drop interface unit 60 and the wavelength multiplexing unit 70. Since there is no need to insert a header into the dropped data frame, the drop interface unit 60 has the same structure as the output interface unit 50 of FIG. 5 except that the header inserter 142 is omitted. The data frame input to the egress unit 100-2 of the edge traffic collector is processed as shown in FIG. 5 and transmitted to the multi-terminal IP router.

The figure which shows the structure of the conventional all-optical router. 1 is a diagram showing an embodiment of a large-capacity optical router according to the present invention. The figure which shows the input interface part of FIG. 2 in detail. FIG. 4 is a diagram illustrating a queue included in the input interface unit of FIG. 3 in detail. The figure which shows the output interface part of FIG. 2 in detail. FIG. 4 is a diagram illustrating a configuration of an optical frame separated into a header and a data frame by the switch in FIG. 3. FIG. 3 is a diagram illustrating an ingress portion of the edge traffic collector of FIG. 2 in detail. FIG. 3 is a diagram showing an egress section of the edge traffic aggregator of FIG. 2 in detail. FIG. 4 is a diagram showing another embodiment of the input interface unit of FIG. 3. FIG. 6 is a diagram illustrating another embodiment of the output interface unit of FIG. 5.

Explanation of reference numerals

Reference Signs List 20 wavelength demultiplexing unit 30 input interface unit 40 optical switch 50 output interface unit 60 drop interface unit 70 wavelength multiplexing unit 75 header processing unit 80 optical switch control unit 90 header reinsertion unit 100 edge traffic aggregation unit 100-1 ingress unit 100-2 egress section

Claims (16)

Many input ports,
Numerous output ports,
An add port for inputting data received from the multi-terminal IP router;
A drop port for outputting data to the composite terminal IP router,
A wavelength demultiplexer that demultiplexes the wavelength signal input through the input port and the add port,
An input interface unit that converts the optical frame input from the wavelength demultiplexing unit into an electric signal and outputs the processed optical frame as an optical frame,
An optical switch for switching an optical frame output from the input interface unit,
An output interface unit that converts the optical frame output by being switched by the optical switch into an electric signal and outputs the processed signal as an optical frame,
A wavelength multiplexer that wavelength-multiplexes the output of the output interface and transmits the output to another optical router;
Of the optical frames switched by the optical switch, a drop interface unit that converts the optical frame output to the composite terminal IP router into an electrical signal and outputs it as an optical frame after processing,
A header processing unit that recognizes header information for controlling an optical router;
An optical switch control unit that controls an optical switch connection state for optical frame switching;
A header reinsertion unit for reinserting a header into the optical router output;
An ingress unit that converts an IP packet input from the composite terminal IP router into an optical frame, and an edge traffic aggregator that has an egress unit that converts the optical frame into an IP packet and transmits the packet to the composite terminal IP router. An optical router characterized by becoming.   2. The optical router according to claim 1, wherein the wavelength demultiplexing unit includes a plurality of wavelength demultiplexers. The input interface section
An optical receiver that converts an optical frame input from the wavelength demultiplexing unit into an electric signal,
A buffer for storing the frame converted by the optical receiver for synchronization,
A header length detector that extracts a header length to separate the header from the frame converted by the optical receiver;
A switch for separating a header and data from a frame output from the buffer;
A queue for storing data separated by the switch before switching for collision resolution,
An optical transmitter that receives data from the queue, restores the frame converted to the electric signal into an optical frame, and transmits the optical frame to the optical switch,
2. The optical router according to claim 1, wherein the header processing unit reads the address with reference to the header separated by the switch, determines an output time, and sends a new header to the header reinsertion unit.   4. The optical router according to claim 3, wherein a guard time having a predetermined interval is provided between a header of the frame input to the switch and a data frame to prevent data loss when separated. The queue of the input interface section is
An electrical switch for switching input data for each destination and outputting the data,
A large number of buffers that are provided for the number of destinations, receive and store data for each destination, and accumulate a certain amount;
4. The optical router according to claim 3, further comprising a combiner for combining outputs of the buffer. The input interface section
An optical receiver that converts an optical frame input from the wavelength demultiplexing unit into an electric signal,
A buffer for storing the frame converted by the optical receiver for synchronization,
A header length detector that extracts a header length to separate the header from the frame converted by the optical receiver;
A switch for separating a header and data from the frame output from the buffer,
A queue for storing a large number of data separated by the switch before switching for collision resolution and for multiplexing output;
Each of the data output from the queue is input, a large number of optical transmitters that restore the frame that has been converted to the electric signal into an optical frame and transmit it to the optical switch,
2. The optical router according to claim 1, wherein the header processing unit reads the address with reference to the header separated by the switch, determines an output time, and sends a new header to the header re-input unit. The output interface section
An optical receiver that converts optical data switched by the optical switch into an electric signal,
A buffer for temporarily storing data output from the optical receiver,
A header inserter for re-inserting a header by a header re-insertion unit into data output from the buffer,
The optical router according to claim 1, further comprising: an optical transmitter for transmitting the data after the header combination as optical data to a next node. The output interface section
Numerous optical receivers that convert optical data switched by an optical switch into an electrical signal,
A number of buffers for temporarily storing data output from the optical receiver,
A combiner for combining data output from the buffer;
A header inserter for re-inserting a header by a header re-insertion unit into data output from the combiner,
The optical router according to claim 1, further comprising: an optical transmitter for transmitting the data after the header combination as optical data to a next node. The ingress part of the edge traffic collector is
Multiple optical receivers for receiving packet data input from the multi-terminal IP router;
A packet processing unit that is connected to each of the optical receivers and performs a function such as packet forwarding;
An address table that provides address information for packet forwarding;
A first electrical switch for switching an output from the packet processing unit for generating an optical frame;
A data frame assembler having a number of buffers and converting packets switched by the first electrical switch into a predetermined number of frames;
A controller and a scheduler for determining an output order and a wavelength of the frame generated by the data frame assembler,
A second electric switch for transmitting a frame whose output order and wavelength are determined by the controller and the scheduler;
A number of header inserters for inserting a header before optical modulation of a frame output from the second electrical switch;
An optical transmission unit configured by a number of optical transmitters that optically modulates the frame after the header combination,
2. The optical router according to claim 1, further comprising: a wavelength multiplexer for wavelength division multiplexing the optical frame after the optical modulation.   The data frame assembler stores the switched packets in destinations according to destinations and stores them in a plurality of buffers. When a certain amount of data is accumulated in each of the buffers, the data is processed according to the buffers, and the controller and the scheduler process the data. 10. The optical router according to claim 9, wherein the output order and the wavelength of the optical frame are determined by grasping the data amount of each buffer of the data frame assembler. The egress part of the edge traffic collector is
A wavelength demultiplexer for demultiplexing the wavelength division multiplexed optical frame dropped by the drop interface unit,
Numerous optical receivers that convert the demultiplexed optical frame into an electric signal,
A data frame disassembler that separates the frame after the electrical signal conversion into IP packet units and separates them into detailed destinations;
A scheduler for controlling an output order of IP packets separated into detail destinations;
A packet processing unit that processes an IP packet output from the data frame disassembler through a process such as forwarding;
An address table for providing an address of a packet processed by the packet processing unit;
An electric switch for switching the packet processed by the packet processing unit to a correct destination IP router;
The optical router according to claim 1, further comprising: a plurality of optical transmitters for optically modulating a packet switched by the electric switch.   After converting the packet input from the multi-terminal IP router into an optical frame of a fixed length according to the destination address by the edge traffic aggregator, the input interface unit performs the optical frame processing through optical / electric / optical conversion. 2. The optical router according to claim 1, wherein after performing switching by the optical switch, the optical interface further transmits the optical frame to the next optical router node or the edge traffic aggregate through optical / electrical / optical conversion at the output interface unit. .   The ingress part of the edge traffic aggregator converts a packet input from the multi-terminal IP router into a data frame of a fixed length according to a destination address, and converts a header having a speed of an integral multiple of the data frame into an integer multiple. The optical router according to claim 1, wherein the optical router is generated, combined with the data frame, and transmitted as an optical frame.   2. The optical router according to claim 1, wherein the egress unit of the edge traffic aggregator receives the optical frame dropped by the drop interface unit, separates the IP frame into IP packets, and transmits the IP packets to the composite terminal IP router.   2. The optical router according to claim 1, wherein the input interface unit includes a header length detector that detects a header start point and a header length, and a switch that separates the header from the data frame and sends the header to the header processing unit.   2. The optical router according to claim 1, wherein the output interface unit includes a header inserter for inserting a new header into the optical frame switched by the optical switch.

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